1. Field of the Invention
The instant invention relates to an easy-to-use locking device for use with hydraulic pistons.
2. Brief Description of the Prior Art
Conventional automotive vehicle bodies have closures, such as hoods, deck lids, or tail gates, which are swingably supported on the vehicle body for movement between open and closed positions. It is also conventional to provide an extendible and collapsible support strut or hold-open device to hold the closure in its open position. These devices can be either mechanical, pneumatic, or a combination thereof.
One type of mechanical device utilizes a pair of telescoping members that are respectively connected to the closure and vehicle body, and which are urged toward an extended position by a spring to hold the closure in its open position. In such devices the spring force has to be overcome to collapse the telescoping members when the closure is moved to its closed position. Examples of such devices are shown in U.S. Pat. Nos. 4,512,600; 3,319,993; 3,891,111; 3,611,892; and 3,851,908. Pneumatic hold-open devices, such as gas spring struts, etc. operate in much the same manner. Examples of such devices are shown in U.S. Pat. Nos. 3,883,126; 3,977,712; and 4,307,875.
The gas springs, or hydraulic pistons, are commonly used in pivoting a trunk lid, hatch-back of an automobile, or rear door of a mini-van, between open and closed positions. The gas springs are subject to wear, leakage, and temperature. A gas spring which, when new, will reliably have a lift in excess of 30 lbs., will, over time, lose its lift capability in colder temperatures. Additionally, over time, the gas will leak out completely, causing failure in all temperatures. In the event of a gas leak, or general wear, the reliability of the gas spring is eliminated and other means must be used to maintain the door in the open position. The rear door of a mini-van can weigh upwards of 100 pounds, and the doors on full sized vans and trucks can be substantially heavier. A door's unexpectedly coming down can cause a substantial amount of physical damage to anyone who is hit. Replacement of the gas springs is expensive, and, in some instances, may not be warranted.
Several patents have issued which have addressed the problem of the failure of the gas spring props, among them U.S. Pat. No. 4,596,383 to Howard. These patents, however, have solved the problem through the addition at the time of manufacture of an ternal locking device. Although a good safety feature, the external locking device does not address the problem of the millions of cars which currently do not have the external locks. Additionally, this is a feature which is either initially placed on cars at the time of manufacture or added separately at a later date.
The instant invention overcomes the problems of the prior art by providing a easy-to-use, inexpensive add-on device to lock the gas springs in the desired position.